1. Field of the Invention
This invention relates to fuel injection apparatus and, more particularly, to fuel injection apparatus for internal combustion engines in which the fuel is pressurized and heated to pressures and temperatures substantially higher than prior art systems and the pressurized and heated fuel is injected into each cylinder in response to predetermined parameters.
2. Background of the Invention
U.S. Pat. No. 2,881,828 discloses a fuel injection system for a diesel engine in which the temperature of the fuel to the injectors is controlled thermostatically. The temperature of the fuel is correlated between the temperature of the fuel in the supply line and in the return line to maintain the temperature within predetermined limits. Excess heat from the fuel return line is exchanged with the fuel in the supply line by an appropriate heat exchanger, or in a second embodiment, the fuel from the return line is introduced directly into the supply line. In the patent, a desired temperature range for the supply fuel is between 150.degree. and 250.degree. F.
U.S. Pat. No. 3,738,334 discloses a pre-heater for heating fuel prior to the carburetor. Heat from the engine exhaust gases is used for pre-heating the fuel.
U.S. Pat. No. 3,762,378 discloses a fuel injection system in which fuel is injected directly into an engine cylinder, and the fuel is preheated prior to the injector.
The fuel line includes a spiral coil disposed in an exhaust passage, and the flow of hot exhaust gases around the coil causes the temperature of the fuel to raise.
U.S. Pat. No. 3,827,409 discloses a fuel injection system in which fuel pressure is varied in response to engine speed or air mass flow. The speed of the engine is sensed, and the pressure of the fuel in an injector manifold or feed rail is varied in response to predetermined parameters based on engine speed or on air mass flow to the engine.
U.S. Pat. No. 3,933,135 discloses a fuel injection system in which fuel is injected into an intake manifold in accordance with predetermined parameters based on air mass flow which is electronically sensed. An electronic system, sensitive to air temperature, humidity, atmospheric pressure, as well as to mass air flow, is used to vary the amount of fuel injected into the manifold.
U.S. Pat. No. 4,040,394 discloses a fuel injection system in which an exhaust gas analyzer is used to provide data to control the supply of fuel to the injectors. A predetermined ratio of fuel and air is supplied to the engine to provide exhaust gases of a predetermined composition.
U.S. Pat. No. 4,051,817 discloses a fuel injection system in which a plurality of sensors are used to provide input to a control system which in turn controls the output of fuel injectors.
U.S. Pat. No. 4,082,066 discloses a fuel injection system which utilizes an electromagnetically actuated injector. A plurality of sensors are used to sense a plurality of engine conditions, and the output from the sensors is transmitted to a post generator, which generates a variable width pulse in response to the input from the engine sensors. The variable width pulse determines the time in which the injectors are open in order to provide the correct amount of fuel flow. A constant pressure fuel source is provided to the injectors and accordingly the flow of fuel from the injectors is in direct proportion to the length of time that the injector valve is open.
U.S. Pat. No. 4,094,275 discloses a fuel system which includes a primary and secondary heating system for vaporizing fuel using exhaust gases. Fuel from the fuel tank is heated prior to the carburetor. A vapor reservoir stores the vaporized fuel under vapor pressure pressurization. The vapor reservoir includes a line for allowing condensed fuel to return to the fuel tank.
U.S. Pat. No. 4,099,499 discloses a heat exchanger usable with the apparatus of the '275 patent.
U.S. Pat. No. 4,109,669 discloses an electronic fuel injection system utilizing a variable injection pressure. Control circuitry for the apparatus is set forth in detail. As is typical in fuel injection systems, fuel is injected into a manifold from a plurality of injectors, and the manifold is in turn connected to a plurality of cylinders. The injectors are typically open to allow for fuel to be injected into the manifold during the exhaust cycle of an engine, and thus while the intake valves are closed. There are a few embodiments of fuel injection systems, such as the '378 patent discussed above, in which fuel is injected directly into a cylinder rather than into a manifold. The '378 apparatus causes the fuel to be ignited spontaneously, such as in a diesel system, as opposed to a typical four stroke cycle gasoline internal combustion engine in which spark plugs are used. In such hypergolic systems, as the '378 patent discusses, the compression of the fuel and air is rather high, and such high compression causes the temperature of the compressed gases to be high enough so that the spontaneous ignition occurs when the fuel is injected into the cylinder.
In the above described patents, various types of systems are used for providing fuel, either through fuel injection or through carburetion, to the various types of internal combustion engines disclosed. In several of the patents, heat exchangers are used to increase the temperature of the fuel prior to the injection or to carburetion, whichever is used. Variable fuel pressure is also suggested in several of the patents as part of a fuel metering system. Also, several of the patents discuss the vaporization of fuel, but none of the patents discuss or disclose systems in which fuel is vaporized by a combination of high pressure and high temperature of the fuel itself.
Some of the patents mentioned above discuss fuel vaporization, but the term "atomization" should preferably be used instead of "vaporization". Partial vaporization may take place, but not substantially complete vaporization. The "vaporization" of the prior art patents appears to be atomization, in which liquid fuel droplets break down into fine liquid particles which move in or with a moving air mass. The vaporization of fuel is the gaseous state of liquid fuel which results from a combination of temperature and pressure, as produced by the present invention.